Collapsible access platform and stair



Dec. 10, 1963 J. B. PASKO, JR

COLLAPSIBLE ACCESS PLATFORM AND STAIR Filed May 4, 1962 :1 HLLJ 3 Sheets-Sheet l flame) Dec. 10, 1963 Filed May 4, 1962 J. B. PASKO, JR 3,113,637

COLLAPSIBLE ACCESS PLATFORM AND STAIR 3 Sheets-Sheet 2 JOSEPH B. PAS/(0 Jr.

Attorney Dec. 10, 1963 J. B. PAsKo, JR

COLLAPSIBLE ACCESS PLATFORM AND STAIR 5 Sheets-Sheet 3 Filed May 4, 1962 United States Patent 3,113,637 CULLAFSIBLE ACIJESS PLATFGRM AND STAIR Joseph E. Pasha, 112, Gary, Ind, assigncr to United States Steel (Jerporation, a corporation of New Jersey Filed May 4, 1962, Ser. No. 192,484 4 Claims. ((11. 162S4) The present invention relates generally to overhead traveling cranes and more particularly to an improved access platform and stair for an overhead traveling crane.

Overhead traveling cranes are ordinarily provided with a suspended access platform and stair at one end to enable the crane operator to reach the catwalk of the crane from whence he can reach the crane cab. Prior to my invention such access platform and stair formed a stationary, fixed structure which depended from and traveled with the main framework of the crane. This depending structure constituted a serious safety hazard particularly in crane installations in warehouses where stored material was stacked to a relatively high level under the crane pathway. One example of such a warehouse is a tin plate mill storage warehouse where coils or packages of tin plated steel are stacked in relatively high ventical piles. Frequently workmen are required to climb to the tops of the piles in order to obtain data from shipping tickets or identification tags attached to the uppermost coils or packages. When it is necessary to climb to the top of piles which are located under the path of the crane access platform and stair, the workman exposed himself to the danger of being struck by the access platform and stair as the crane moved overhead due to the reduced headroom under the access platform and stair compared with the headroom under the remainder of the crane structure.

It is, accordingly, the primary object of my invention to provide an improved and novel collapsible access platform and stair for an overhead crane which can be retracted upwardly when the crane is operating and suspended downwardly into operative position when the crane is stopped.

This and other objects will become more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a side elevational view partly in section showing the collapsible access platform and stair of the invention in lowered operative position;

FIGURE 2 is a vertical sectional view taken along the line II-II of FIGURE 1;

FIGURE 3 is a view similar to FIGURE 1 but showing the collapsible access platform and stair of the invention in retracted position;

FIGURE 4 is an enlarged detail partial end view taken along the line IV-IV of FIGURE 1;

FIGURE 5 is a side elevational view taken along the line VV of FIGURE 4; and

FIGURE 6 is a plan view taken along the line VIVI of FIGURE 3.

Referring more particularly to the drawings reference numeral 2 designates an overhead crane bridge framework having transversely extended 8 depending from the underside thereof in spaced parallel relation. A longitudinal channel 12 is connected with and extends between transverse channels 4 and 6 along the undersurface of one side of the bridge framework. A flat upright plate extends longitudinally along the side of the bridge framework opposite to and parallel with the channel 12. As best shown in FIGURE 3, the plate 16 is longer than the channel 12.

Reference numeral 14 designates a substantially rectangular platform which includes an underframe made up of two paralel elongated angles 16 and 17 which form two opposite sides of the platform underframe, and two elongated angles 18 which are connected with and extend welded channels 4, 6 and between angles 16 and 17. Angles 18 form the ends of.

lel with the end angles 18. A metal floor plate 22 iswelded to and supported by the underframe. The angles 16 and 17 project beyond one end of the floor plate and each has a bearing block 24 laflixed to the inner surfaceof its projecting end. A shaft 26 is journaled in the bearing blocks 24. A locking plate 28 having a depending flange 30 at each end is mounted on the shaft 26 between the projecting ends of the angle members 16 and 17. The shaft 26 passes through holes in the flanges 30" and is rigidly secured to the flanges by means of set screws 32. As will become apparent, when the platform is in lowered position as shown in FIGURE 1, the locking. plate 28 forms a continuation of the floor plate 22. When the platform is raised to retracted position, as shown in FIG- URE 3, the locking plate is pivoted by shaft 26 for a purpose which will be more fully described hereinafter.

As best shown in FIGURES 1 and 4, a toe plate 36 extends along one side of the platform 14 and is securedat both of its ends to channel 17 by means of bolts 38. A toe plate 41} extends along the opposite side of the platform 14 and is connected by one end to channel 16 by means of a bolt 42. The opposite end of toe plate 40' is provided with an opening which rotatably receives the shaft 26 so that this end of toe plate 40* is carried by the. shaft.

As shown in FIGURE 4, one end 44 of shaft 26 is squared and projects outwardly of toe plate '40. A locking element 45 having a latch plate 46 projecting therefrom and an eccentric 48 formed integral therewith is mounted, by means of a cap screw 56*, on the squared.

projecting end 44 of shaft 26 for rotation therewith. The locking element 45 is provided with a square opening for receiving the squared end of shaft 26.

The platform 14 is suspended from plate 10* and channel 12 of the bridge framework by means of four hangers 52, 54, 56 and 58 (FIGURES 1-4). Hangers 52 and 5-4 are pivotally connected at their upper ends to plate 10 by means of bolts 66. Hangers 56 and 58 are connected at their upper ends to channel 12 by means of bolts 62 (FIGURES 1 and 2). The bottom ends ofhangers 52 and 54 are disposed between toe plate 36 and angle 17 and are pivotally secured to angle 17 by means of the bolts: 38 which pass through the toe plate 36 and the bottom ends of the hangers 52 and 54, as best shown in FIGURE 4. The bottom of hanger 56 is pivotally mounted on shaft 26 between angle 16 and toe plate 40* (FIGURE 4). The bottom of hanger 58 is pivotally mounted on bolt 42 between toe plate 46 and angle 16' (FIGURE 1). A handrail 64 is pivotally connected with and extends between hangers 52 and 54. A similar handrail 66 is pivotally connected with and extends between hangers 56 and 58 (FIGURES 1, Ziand 3).

A lever bracket 68 is pivotally connected at its sides adjacent its forward end to angles 16 and 17 and extends therebetween parallel with transverse angles 18 and 20. The lever bracket is pivotally secured to the angles 16 and 17 by means of bolts 70" (FIGURES 1 and 2). A ring 72 is formed on the rearward end of bracket 68 intermediate its sides for receiving The lever bracket 68 normally extends angularly and downwardly from the platform 14, as best shown in FIG URE 1. A raised rib 76 is provided along the upper surface of the lever 68 extending from one side thereof to the other adjacent its pivoted end for a purpose which will become apparent.

A stair 78 is pivotally connected at its upper end to gusset plates as by means of bolts 82. The gusset plates are welded or otherwise rigidly attached to channel 6 of the bridge framework. A depending rectangular bar 84 extends across the bottom of the stair 78 land is adapted to Patented Dec. 10, 1963.

the end of a wire rope 74;

3 fit into a rectangular opening 86 in the floor plate 22 to lock the stair in place when the platform and stair are in lowered position, as shown in FIGURE 1.

The drive mechanism for raising and lowering the collapsible access platform and stair includes a reversible gear-motor 83 mounted on a shelf 91} which is attached to and projects from the bridge framework 2 (FIGURES l and 2). A sprocket 92 keyed on the drive shaft 94 of the gear-motor 88 drives a shaft 96 through a chain 9? and sprocket 109. The shaft 96 is journaled in pillow blocks 10 1 mounted on the bridge 'fnamework below shelf 96 and has a drum 102 keyed thereon for winding and unwinding wire rope 74. One end of rope 74 is attached to ring 72 on the lever bracket 68- and the other end is clamped on the drum. Rotation of drum 162 in counterclockwise direction, as viewed in FIGURE 1, will raise the collapsible access platform and stair to retracted position as shown in FIGURE 3. Rotation of the drum in clockwise direction eflects lowering of the platform and stair.

A safety latch, designated generally by reference numeral 104, is provided for locking the platform and stairs in retracted position (FIGURES 1 and 6). Safety latch 104 includes a solenoid 196 mounted on a ledge 1113 which is rigidly suspended from bridge framework 2 by means of vertical arms 110. A lever arm 112 is pivotally attached by one end to the projecting end of the springloaded armature 114 of solenoid 1% by means of a link 116. The lever arm 112 is pivoted intermediate its ends on a pivot pin 113 which extends between two ears 121} formed on two of the arms 111). A horizontal plate 122 is secured to the underside of the free end of lever arm 112. A latch arm 124 is pivotally mounted by one end on pivot pin 11% between ears 120 and normally extends adjacent to and projects beyond the free end of lever arm 112 (FIGURE 6). Plate 122 projects underneath the latch arm 124'. Thus, when solenoid 196 is energized and armature 114 is retracted the rearward end of lever 112 will be pulled downwardly and the lever arm will be pivoted in counterclockwise direction around pivot pin 118. This will cause the free end of the lever arm to raise and lift plate 122 against the underside of latch arm 124 so that the latch arm will be pivoted upwardly around the pivot pin 118. De-energization of solenoid we will cause the spring-loaded armature 114 to be projected and pivot lever arm 112 in clockwise direction around pivot pin 113. Clockwise pivotal movement of lever arm 112 will cause latch arm 124 to drop by its own weight to horizontal position bearing on the plate 122.

-In operation, when it is desired to raise the platform and stair to retracted raised position, gearmotor St is energized to rotate shaft 96 in counterclockwise direction. This causes rotation of rope drum 1112 in counterclockwise direction and winding of wire rope 74 on the drum. As the rope begins to wind on the drum it pivots lever bracket 68 upwardly causing the rib '76 to engage the bar 84 on the bottom of the stair '78- and lift it out of the opening 86 in the floor plate 22 so that the lower end of the stair is free to slide on top of the floor plate. Winding of the rope is continued until the platform and stair are raised to the retracted position shown in FIGURE 3. While the platform and stair are being raised, eccentric 48 of locking element 45 engages the bottom flange of channel 12 and causes shaft 26 to rotate and locking plate 28 to bear against the underside of one of the treads of stair '78. At the same time latch mm 124- of safety lock 104 is raised by the latch plate 46. After the latch plate 46 passes the nose of the latch arm 124', the latch arm drops back to horizontal position and engages the latch plate as shown in FIGURES 3 and 6. When the platform and stair have reached raised position gearmotor 83 is stopped. Since the downward stresses inherent in the raised platform and stair are in opposite directions, clockwise and counterclockwise, respectively, as shown by the arrows in FlGURE 3, they will be locked in raised position so long as the latch arm 124 engages latch plate as to force the locking plate 28 against the underside of the tread. This insures the platform and stair remaining in raised retracted position even though failure of the wire rope should occur.

When it is desired to lower the platform and stair, solenoid 1% is energized to retract armature 114 and pivot lever arm 112 and latch arm 124 upwardly so that cam lock 46 is disengaged. Gearmotor 88 is then energized to rotate drum 1M in clockwise direction, as viewed in FIGURE 3, to unwind the rope 74 from the drum. As the platform is being lowered, the weight of the locking plate 28 causes the shaft 26 to rotate and the locking plate to resume its horizontal position. When the platform md stair have been lowered to operative position, gearmotor 38 is de-energized.

It will be noted that, if desired, upper and lower limit switches (not shown) may be provided to de-energize gearmotor 83 when the platform and stair reach raised and lowered positions, respectively. As an added safety feature the control circuit for the gearmotor (not shown) can be connected with the control circuit of the crane so that the crane cannot be operated if the platform and stair are not in raised position.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. The combination with a collapsible frame suspended from an overhead beam including hangers depending from said beam, and a platform pivo-tally mounted on said hangers, of a stair having its upper end pivoted to said beam at one side of said platform and its lower end slidably bearing on said platform, hoist means for drawing the suspended platform up toward the beam on the side on which the stair is pivoted, a cross shaft journaled in said platform, a detent on said shaft, a plate rigid with said shaft adapted to be engaged by said stair when the platform is raised, and latch means engageable with said detenit when said platform is raised.

2. The combination with a collapsible frame suspended from an overhead beam including hangers depending from said beam, and a platform pivotally mounted on said hangers, of a stair having its upper end pivoted to said beam at one side of said platform and its lower end slidably bearing on said platform, and hoist means for drawing the suspended platform up toward the beam on the side on which the stair is pivoted, said platform having a hole therethrough adjacent one side, and the lower end of said stair having a downward projection adapted to fit in said hole when said platform is in its lowered position.

3. The combination as defined in claim 2 characterized by said hoist means including a lever pivoted to said platform, and means on said lever adapted to raise said projection on operation of said hoist means.

4. The combination as defined by claim 1 characterized by said plate normally constituting a co-planar continua tion of said platform when said platform is in lowered position, and means whereby the plate is restored to coplanar position with said platform when said platform is lowered.

References Qitctl in the file of this patent UNITED STATES PATENTS 178,457 Nevins June 6, 1876 

1. THE COMBINATION WITH A COLLAPSIBLE FRAME SUSPENDED FROM AN OVERHEAD BEAM INCLUDING HANGERS DEPENDING FROM SAID BEAM, AND A PLATFORM PIVOTALLY MOUNTED ON SAID HANGERS, OF A STAIR HAVING ITS UPPER END PIVOTED TO SAID BEAM AT ONE SIDE OF SAID PLATFORM AND ITS LOWER END SLIDABLY BEARING ON SAID PLATFORM, HOIST MEANS FOR DRAWING THE SUSPENDED PLATFORM UP TOWARD THE BEAM ON THE SIDE ON WHICH THE STAIR IS PIVOTED, A CROSS SHAFT JOURNALED IN SAID PLATFORM, A DETENT ON SAID SHAFT, A PLATE RIGID WITH SAID SHAFT ADAPTED TO BE ENGAGED BY SAID STAIR WHEN THE PLATFORM IS RAISED, AND LATCH MEANS ENGAGEABLE WITH SAID DETENT WHEN SAID PLATFORM IS RAISED. 